The present invention relates to an apparatus and a method for fastening and holding insulation. In particular, the apparatus and method relate to fastening insulation around air ducts commonly used for heating and air conditioning. The apparatus comprises a flexible disk of relatively large surface area which, when attached by a fastener, flexes below the plane of the insulation and therefore applies force and tension to the insulation without reducing the insulation value of the insulation.
Very often wires are used for encircling, and thereby attaching, insulation to metal duct work in, for instance, air conditioning and heating applications. Such means for securing insulation to the metal duct work often results in xe2x80x9cbellyingxe2x80x9d of the insulation or in some way not allowing the insulation to come into full contact with the duct work, reducing the efficiency of the insulation, and also enabling the insulation to completely become disattached from the ducts. This is particularly troublesome in air conditioning and heating applications because the insulation is commonly applied in rooms and other structural areas that are not meant to be heated or air conditioned. This either causes condensation, which destroys insulation value and damages walls and floors, or corrosion of metals including the duct work itself. Further, such areas tend to be inacessible once the duct work is installed, rendering re-fastening of the insulation extremely difficult.
In many cases duct tape is used to hold the insulation to the sheet metal duct work. Even more so than wire, tape has a tendency to loosen and the insulation is thereby separated from the duct causing the condensation and corrosion problems mentioned above.
Numerous innovations for fasteners, some for insulation, have been known in the art. For example, in the fields of plaster repair or roofing, various screw-washer combinations have been suggested. Even though these innovations may be suitable for the specific individualistic purposes to which they are designed, they differ from the present invention. The complexity of such devices and/or the inapplicability of such devices to accomplish the fastening of insulation to metal duct work makes the use of such devices incapable of solving the problems of insulation-to-duct-work attachment. Moreover, the use of the flexible disk of this invention for attaching insulation to air ducts is heretofore unknown in the prior art.
Spring-type washers, referred to as dished or conical washers, have been employed to secure screwheads and nuts against loosening, such as in U.S. Pat. No. 3,628,584 to Gutshall. Washers of this type are inapplicable to insulation uses because their diameter and surface area is too small, they lack the necessary flexibility and require substantial flattening force which would crush the insulation and destroy the insulation properties. Similarly, resilient pressure plates for attaching roofing nails and holding shingles, as in U.S. Pat. No. 5,407,313 to Bruins et al., have significantly smaller diameters than the present invention and require substantial force to flex them in order to hold the shingle. Each of these qualities, particularly in combination, are undesirable in holding air conditioning type insulation.
It is therefore an object of the present invention to provide an improved means for fastening insulation to an air conditioning or heating duct. It is a further object of the invention to provide a fastener having an area large enough to apply force in holding the insulation without distortion of the insulation upon fastening, and having the proper amount of flexibility to hold the insulation without crushing it and destroying the insulation properties.
The present invention relates to a flexible, plastic disk washer having an extended diameter, and having a central circular opening for accommodating a fastening device, such as a galvanized metal screw.
In accordance with the present invention, the disk is molded from plastic material in a convex upper surface configuration. The disk has a disk top and a disk centrally positioned in the disk top. An opening is centrally located in the disk washer for receiving a fastening apparatus, such as a screw. The disk washer has a thickness sufficient to support the screw head which also allows the use of power tools to turn the screw without burning through the thinner dimension of the disk. The disk extends radially in all directions from its center, sloping downward at an angle of about 10xc2x0, forming a disk diameter of from about 1{fraction (1/2xe2x80x3)} to about 4xe2x80x3. The thickness of the disk body is about 0.06xe2x80x3. An outer, vertical rim is located at the disk circumference providing an edge for contacting the insulation and holding it in place.
The rim edge can also contain serrations for preventing the disk from turning as the fastening screw is tightened. The disk has an overall height of about 0.25xe2x80x3 measured from the bottom of the vertical rim to the top of the disk washer.
The design and dimensions of the disk allow for pressure to be uniformly applied to hold the insulation in place. In conjunction with the disk""s thickness dimensions, the disk is designed to flex downward when the screw is tightened to a point where the bottom of the disk washer extends below the plane formed by the bottom of the disk rim. In this position of deformity, the disk rim provides enough pressure to hold the insulation without crushing it. Further, when the disk is properly applied it becomes deformed to the extent that the upper surface becomes concave, allowing the full surface area of the underside of the disk to come into contact with the insulation. Thus, this surface area supplements the holding force provided by the disk rim and distributes the force to a large surface area of the insulation.